The present invention relates to a light receiving/emitting element module which is formed by optically connecting a light receiving/emitting element and an optical fiber which are used for optical communications, and a manufacturing method thereof.
In the field of optical communications, a light emitting element for emitting light such as a laser diode and a light receiving element for receiving light such as a photodiode have been used. By optically connecting these light emitting elements and light receiving elements (hereinafter, these are collectively referred to as a light receiving/emitting element) with precision, the communication level of optical communications rises.
When the light receiving/emitting element and optical fibers are optically connected, in a case where a single mode optical fiber whose core diameter is approximately 10 xcexcm and the light receiving/emitting element are optically connected, precision of a degree of several xcexcm is required, and in a case where a multi-mode optical fiber whose core diameter is 50 xcexcm or more, and the light receiving/emitting element are connected, precision of a degree of several tens xcexcm is required when the optical fiber and light receiving/emitting element are aligned and fixed.
Conventionally, as one method for precisely aligning optical fibers and light receiving/emitting element as mentioned above, for example, a moving stage having high moving precision was prepared, the optical fiber was moved by means of the moving stage to adjust the optical axis of the light receiving/emitting element and the optical axis of the optical fiber so as to coincide with each other. In another method, a substrate having a V-shaped groove was prepared, the axis of the V-shaped groove formed at the substrate and the optical axis of the light receiving/emitting element were matched with each other in advance, and the optical fiber was inserted and fixed into the V-shaped groove, whereby the optical axis of the light receiving/emitting element and the optical axis of the optical fiber were matched with each other.
Also, in a case where the optical axis of the light receiving/emitting element and the optical axis of the optical fiber are matched with each other by using a moving stage, the optical fiber and light receiving/emitting element are fixed by using, for example, a welding laser, etc., in an aligned condition.
However, as mentioned above, in a case where the optical axis of a light receiving/emitting element and the optical axis of an optical fiber were matched with each other by using a moving stage, and the optical fiber and light receiving/emitting element were fixed to each other by using a welding laser, etc., a moving stage and a welding laser which were extremely expensive and large in scale were required. Moreover, since aligning and fixing operations between the light receiving/emitting element and optical fiber were not easy, there were problems in that production efficiency was not good, and the costs for a module which was formed by fixing the light receiving/emitting element and optical fiber increased.
In the case where a light receiving/emitting element and optical fiber are aligned and fixed by using a substrate with a V-shaped groove, in comparison with the case where a moving stage is used, aligning and fixing operations between the light receiving/emitting element and optical fiber become easier. However, unlike a general light receiving/emitting element in which a crystal cleavage plane is formed as a light receiving/emitting surface, when a face light receiving/emitting type of a light receiving/emitting element in which a crystal face direction (surface perpendicular to the cleavage plane) is formed as a light receiving/emitting surface and an optical fiber are connected to each other, a problem occurs. That is, when the light receiving/emitting element is loaded on, for example, an element loading substrate, and an optical fiber are inserted and fixed into a V-shaped groove at the substrate, etc., the connection end face of the optical fiber cross at right angles to the light receiving/emitting surface of the light receiving/emitting element, and the optical axis of the light receiving/emitting element and optical axis of the optical fiber also cross at right angles, and therefore, the light receiving/emitting element and optical fiber cannot be optically connected to each other in this condition.
Therefore, when a face light receiving/emitting type of light receiving/emitting element and an optical fiber are optically connected, between the light receiving/emitting element and optical fiber, it is necessary that a mirror for reflecting light is provided, or the light receiving/emitting element is fixed at the side surface of the substrate, and the light receiving/emitting element and optical fiber are aligned and fixed. As a result, the device construction becomes complicated and the aligning and fixing operations become difficult, and also, cost for a module which is formed by fixing the light receiving/emitting element and optical fiber increases.
The invention is made in order to solve the above problems in the prior-art, and the object thereof is to provide a light emitting and receiving element module in which a face light receiving/emitting type of a light receiving/emitting element and an optical fiber are easily aligned and fixed to each other with precision, and whose cost is low, and a manufacturing method thereof.
In order to achieve the above object, the invention has characteristic aspects as follows. That is, a first aspect of the light receiving/emitting element module is characterized in that the element loading surface of an element loading substrate with a light receiving/emitting element loaded and a connection end face of a ferrule with an insertion hole for an optical fiber to be optically connected to the light receiving/emitting element are disposed opposite to each other, and at least at the connection end face side of said ferrule, a ferrule side fitting part into which an aligning member between the optical fiber and light receiving/emitting element is inserted and fitted is provided, at least at the element loading surface side of the element loading substrate opposite to said ferrule side fitting part, a substrate side fitting part into which the aligning member is inserted and fitted is provided, an aligning member is commonly provided at the ferrule side fitting part and substrate side fitting part, whereby the ferrule and element loading substrate are fixed, and the optical fiber inserted into the optical fiber insertion hole and the light receiving/emitting element are aligned and optically connected.
A second aspect of the light receiving/emitting element module of the invention is characterized in that the aligning member is a spherical member in the light receiving/emitting element module of the first aspect.
Furthermore, a third aspect of the light receiving/emitting element module of the invention is characterized in that, to the light receiving/emitting element, at least either one of flexible wiring and a lead terminal to electrically connect said light receiving/emitting element to the connection part at the element loading substrate external part is connected in the light receiving/emitting element module of the first aspect.
Furthermore, a fourth aspect of the light receiving/emitting element module of the invention is characterized in that, the ferrule and element loading substrate are disposed and fixed so that the connection end face of the ferrule is diagonal to the light receiving/emitting surface of the light receiving/emitting element in the light receiving/emitting element module of the first aspect.
Furthermore, a fifth aspect of the light receiving/emitting element module of the invention is characterized in that, between the connection end face of the ferrule and the element loading surface of the element loading substrate, an inclination adjusting means for adjusting the angle between the light receiving/emitting surface of the light receiving/emitting element and the connection end face of the ferrule is provided, and the angle between the connection end face of the ferrule and the light receiving/emitting surface of the light receiving/emitting element is an angle which is set in advance in the light emitting and receiving element module of the first or second aspect.
Furthermore, a sixth aspect of the light receiving/emitting element module of the invention is characterized in that the optical fiber is fixed into the optical fiber insertion hole so that the connection end face side is further projected toward the light receiving/emitting element side rather than the connection end face of the ferrule, and the space between the connection end face of the optical fiber and the light receiving/emitting surface of the light receiving/emitting element is a space set in advance in the light receiving/emitting element module of the first or second aspect.
Furthermore, a seventh aspect of the light receiving/emitting element module of the invention is characterized in that the light receiving/emitting surface side of the light receiving/emitting element is covered with a light transmittable material in the light receiving/emitting element module of the first aspect.
Furthermore, an eighth aspect of the light receiving/emitting element module of the invention is characterized in that the connection end face of the optical fiber is butted against the surface of the light transmittable material, and the space between the connection end face of the optical fiber and the light receiving/emitting surface of the light receiving/emitting element is a space set in advance in the light receiving/emitting element module of the seventh aspect.
Furthermore, a ninth aspect of the light receiving/emitting element module of the invention is characterized in that the set space is several xcexcm through several tens xcexcm in the light receiving/emitting element module of the sixth or eighth aspect.
Furthermore, a tenth aspect of the light receiving/emitting element module of the invention is characterized in that the light receiving/emitting element includes one or more light emitting elements and one or more light receiving elements, and a partition groove for partitioning a light emitting element loading part and light receiving element loading part of the element loading substrate is provided between the light emitting element loading part and light receiving element loading part in the light receiving/emitting element module of the first aspect.
Furthermore, an eleventh aspect of the light receiving/emitting element module of the invention is characterized in that a projecting part to be fitted into the partition groove is formed at the connection end face side of the ferrule so as to project toward the element loading substrate side in the light receiving/emitting element module of the tenth aspect.
Furthermore, a twelfth aspect of the light receiving/emitting element module of the invention is characterized in that a projecting part is formed at the connection end face side of the ferrule so as to project between the light emitting element loading part and light receiving loading part of the element loading substrate in the light receiving/emitting element module of the first aspect.
Furthermore, a thirteenth aspect of the light receiving/emitting element module of the invention is characterized in that the connection end face of the optical fiber to be optically connected to the light emitting elements is the identical surface to the ferrule connection end face, and an attenuator to cover the connection end face of the optical fiber is provided in the light receiving/emitting element module of the tenth, eleventh, or twelfth aspect.
Furthermore, the manufacturing method for the light receiving/emitting element module of the invention is characterized in that, at least at the element loading surface side of the element loading substrate onto which the light receiving/emitting element is loaded, a substrate side fitting part is provided into which an aligning member is inserted and fitted to the light receiving/emitting element and optical fiber to be optically connected to said light receiving/emitting element, at least at the connection end face side of the ferrule with the optical fiber insertion hole formed, a ferrule side fitting part is provided into which the aligning member is inserted and fitted, the element loading surface of the element loading substrate and the connection end face of the ferrule are disposed opposite each other to oppose the substrate side fitting part to the ferrule side fitting part, and an aligning member which is common for the substrate side fitting part and ferrule side fitting part which are opposite to each other is interposed between them to fix the ferrule and the element loading substrate, whereby a light receiving/emitting element module in which an optical fiber inserted in the optical fiber insertion hole and the light receiving/emitting element are aligned and optically connected to each other is manufactured.
In the invention of the above construction, the element loading surface of the element loading substrate onto which the light receiving/emitting element is loaded and the connection end face of the ferrule which is optically connected to the light receiving/emitting element and has an optical fiber insertion hole are disposed opposite each other. In this condition, by inserting the optical fiber into the optical fiber insertion hole of the ferrule, the optical axis of the optical fiber and the optical axis of the light receiving/emitting element coincide with each other. Therefore, without providing a mirror for reflecting light, the connection end face of the optical fiber and the light receiving/emitting surface of the light receiving/emitting element can be opposed to each other with precision, whereby the optical fiber inserted into the optical fiber insertion hole and the light receiving/emitting element can be aligned and optically connected to each other.
In the invention, at least at the connection end face side of the ferrule, a ferrule side fitting part into which a member for aligning the optical fiber and light receiving/emitting element is inserted and fitted is provided, and at least at the element loading surface side of the element loading substrate opposite to the ferrule side fitting part, a substrate side fitting part into which the aligning member is inserted and fitted is provided. Therefore, an aligning member which is common for the ferrule side fitting part and substrate side fitting part is interposed between them, and the ferrule and the element loading substrate are fixed, whereby the optical fiber inserted in the optical fiber insertion hole and the light receiving/emitting element are aligned and optically connected to each other. Thus, by only inserting the optical fiber into the optical fiber insertion hole of the ferrule, a light receiving/emitting element module can be manufactured in which the optical fiber and light receiving/emitting element are easily aligned and fixed with precision.
Therefore, according to the light receiving/emitting element module of the invention, without moving at least either one of the optical fiber and light receiving/emitting element by a moving stage, for example, a face light receiving/emitting type of a light receiving/emitting element and an optical fiber can be aligned and fixed with precision by extremely simple construction, whereby cost for the light receiving/emitting element module can be reduced.
Also, according to the light receiving/emitting element module of the invention in which the aligning member is spherical, by inserting and fitting the aligning member into the ferrule side fitting part and the substrate side fitting part, aligning of the optical fiber and light receiving/emitting element can be performed not only in the plane direction orthogonal to the optical axes thereof but also in the optical axis direction at the same time, whereby manufacturing of the light receiving/emitting element module can be made easier.
Furthermore, according to the light receiving/emitting element module of the invention in which at least either one of the flexible wiring and lead terminal to be electrically connected to the connection part of the element loading substrate external part is connected to the light receiving/emitting element, by using the flexible wiring and lead terminal, the light receiving/emitting element can be easily connected to the connection part of the element loading substrate external part.
Furthermore, according to the light receiving/emitting element module of the invention in which the ferrule and element loading substrate are disposed and fixed so that the connection end face of the ferrule is diagonal to the light receiving/emitting surface of the light receiving/emitting element, the angle between the connection end face of the ferrule and the light receiving/emitting surface of the light receiving/emitting element is properly set, whereby harmful influence due to light reflection occurring between these surfaces is suppressed. Therefore, by using the light receiving/emitting element module of the invention, the quality of optical communications can be satisfactorily improved.
Furthermore, according to the light receiving/emitting element module of the invention in which an inclination adjusting means for adjusting the angle between the light receiving/emitting surface of the light receiving/emitting element and the connection end face of the ferrule is provided between the connection end face of the ferrule and element loading surface of the element loading substrate, by this inclination adjusting means, the angle between the connection end face of the ferrule and the light receiving/emitting surface of the light receiving/emitting element can be easily adjusted to an optimum set angle without fail. Thereby, providing of a light receiving/emitting element module with high quality and reliability becomes possible.
Furthermore, according to the light receiving/emitting element module of the invention in which the optical fiber is fixed in the optical fiber insertion hole so that the connection end face side is further projected toward the light receiving/emitting element side rather than the connection end face of the ferrule, and the space between the connection end face of the optical fiber and the light receiving/emitting surface of the light receiving/emitting element is a space set in advance, or the connection end face of the optical fiber are in contact with the light receiving/emitting surface of the light receiving/emitting element, the space between the connection end face of the optical fiber and light receiving/emitting surface of the light receiving/emitting element is maintained at an optimum. Thereby, optical connection between the optical fiber and the light receiving/emitting element can be properly made.
Furthermore, according to the light receiving/emitting element module of the invention in which the light receiving/emitting surface side of the light receiving/emitting element is covered with a light transmittable material, the light receiving/emitting surface of the light receiving/emitting element is protected from an external power by the light transmittable material.
Furthermore, according to the light receiving/emitting element module of the invention in which the connection end face of the optical fiber is butted against the surface of the light transmittable material, and the space between the connection end face of the optical fiber and the light receiving/emitting surface of the light receiving/emitting element is a predetermined space, by only butting the connection end face of the optical fiber against the surface of the light transmittable material, the space between the connection end face of the optical fiber and the light receiving/emitting surface of the light receiving/emitting element can be more easily set to an optimum space for optical connection.
Furthermore, according to the light receiving/emitting element module of the invention in which the space is set to several xcexcm through several tens xcexcm, if the light receiving/emitting element is a face light emitting laser or face light receiving photodiode which has been currently used, the space between such a light receiving/emitting element and optical fiber becomes optimum, whereby optical connection quality between the light receiving/emitting element and optical fiber can be improved.
Furthermore, according to the light receiving/emitting element module of the invention in which the light receiving/emitting element includes one or more light emitting elements and one or more light receiving elements, and a partition groove for partitioning a light emitting element loading part and light receiving element loading part is provided between the light emitting element loading part and light receiving element loading part of the element loading substrate, by using the partition groove, the light emitting element loading part and light receiving loading part can be partitioned without fail. Particularly, according to the light receiving/emitting element module of the invention in which, at the connection end face side of the ferrule, a projecting part to be fitted into the partition groove is formed so as to project toward the element loading substrate side, the light emitting element and light receiving element are light-blocked, whereby harmful influences for optical communications due to direct entrance of light emitted from the light emitting element into the light receiving element can be prevented.
Furthermore, according to the invention in which the connection end face of the optical fiber to be optically connected to the light emitting element is not projected from the connection end face of the ferrule, and made identical to the ferrule connection end face, and an attenuator is provided at said optical fiber connection end face, the intensity of the light to be made incident on the optical fiber from the light emitting element can be easily controlled without fail by the attenuator.
Furthermore, according to the light receiving/emitting element module manufacturing method of the invention, the light receiving/emitting element module having excellent effects as mentioned above can be easily manufactured without fail at a low cost.